江西省耕地土壤碳氮比空间变异特征及其影响因素

以江西省2012年测土配方施肥项目采集的16 582个耕地表层(0~20 cm)土壤样点数据,运用普通克里格和回归分析方法,对江西省土壤碳氮比(C/N)空间变异特征及其影响因素进行分析.结果表明江西省土壤C/N在2.98~52.67之间,平均值为11.72,变异系数为25.17%,呈中等变异性.经半方差分析,土壤C/N的块金效应为88.44%,其空间变异受结构性和随机性因素共同影响,但随机性因素的影响更大.土壤C/N空间分布较为平滑,高值区主要分布在九江市彭泽县、萍乡市上栗县和抚州市乐安县.地形因子、耕地利用方式、成土母质、土壤类型和氮肥施用量对土壤C/N空间变异影响均显著(P0.05),但影响程度不一.地形因子可解释0.3%的土壤C/N空间变异,耕地利用方式的独立解释能力为1.4%,成土母质的独立解释能力为2.4%,土类、亚类和土属的独立解释能力分别为2.7%、3.6%、5.5%.氮肥施用量对土壤C/N空间变异的独立解释能力最高,为33.4%,是引起江西省土壤C/N空间变异最主要的因素.

Spatial Variability of C-to-N Ratio of Farmland Soil in Jiangxi Province

Spatial variability of soil carbon-to-nitrogen ratio (C/N) at the provincial scale was analyzed using ordinary kriging methods. The effects of the factors influencing C/N were quantified by regression analysis based on 16,582 points of surface soil samples (0-20 cm) collected during the project of soil-test-based formulated fertilization in Jiangxi Province in 2012. The results showed that soil C/N ranged from 2.98 to 52.67, with an average of 11.72. The coefficient of variation was 25.17%, suggesting moderate variability. The nugget-to-sill ratio was 88.44%, meaning that the stochastic factors played a more important role in the spatial variability of soil C/N between the structural and stochastic factors. The spatial distribution of soil C/N was relatively smooth and the high-value areas were mainly distributed in Pengze County-Jiujiang City, Shangli County-Pingxiang City, and Lean County-Fuzhou City. The terrain factors, farmland-use type, parent material, soil type, and the level of nitrogen fertilizer had significant impacts on the spatial variability of soil C/N (P<0.05), but the degree of influence was different for each factor. Soil C/N indicated a significant positive Pearson''s correlation with elevation and the slope of slope (P<0.05). The terrain factors explained 0.3% of the spatial variability of soil C/N and the farmland-use could explain 1.4%. The explanatory power of soil groups, subgroups, and soil family were 2.7%, 3.6%, and 5.5% respectively. The level of nitrogen fertilizer could explain 33.4% of the spatial variability of soil C/N, which showed that the amount of nitrogen fertilizer was the main factor that controls the spatial distribution of soil C/N.